Talk:Experience curve effects

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Contents 1 Sharpening the axe vs. chopping the tree 2 Power law or exponential law? 3 Cumulative average cost? 4 Moore's Law 5 The "steep" learning curve misnomer 6 Ebbinghaus?

[edit] Sharpening the axe vs. chopping the tree

A related, but subtly different, I think, idea, is the relationship between efficiency for a method compared to another method on different time scales. For instance, a macintosh one-button mouse and GUI is much more efficient on short time scales but a complicated keystroke-based thingy like vim is more efficient on long timescales after becoming comfortable with it. (I don't like either.) Similarly, a chording keyboard can theoretically be used more quickly than a regular computer keyboard, but the time it takes to learn makes it unusable in the short term, compared to hunt and peck typing. Is there a word for this concept? - Omegatron 23:11, May 8, 2005 (UTC)

This is spoken about as the difference between the "learning phase" and the "automated phase" in this article: http://jef.raskincenter.org/humane_interface/summary_of_thi.html - Omegatron 02:47, Jun 17, 2005 (UTC)

A relevant quote from Abraham Lincoln:

If I had six hours to chop down a tree, I'd spend the first four hours sharpening the axe.

This illustrates the tradeoff between preparation time vs. execution time for a given task. The more trees one needs to chop, the greater the return on a unit of axe-sharpening time. — Teratornis 14:52, 23 August 2006 (UTC)

Another is (paraphrasing) "Given ten hours to accomplish a task, an engineer will spend nine hours learning to do it in one hour." - 209.130.150.117 04:58, 4 March 2007 (UTC)

[edit] Power law or exponential law?

The article states "Each time cumulative volume doubles, ... costs ... fall by a constant ... percentage". This would imply that mathematically the effect approximates a power law:

where v is volume, c is cost, and B and α > 0 are constants. In fact it is more likely that

where A is an asymptotic unit cost greater than zero.

Another possibility is that "each time cumulative volume increases by a fixed amount, costs fall by a constant percentage": this would imply that costs decay exponentially, with formula

Is there evidence for one of these "laws" over another?

Note that for the related area of response time in individual learning of repeated tasks, Heathcote, Brown and Mewhort in their paper The Power Law repealed: the case for an Exponential Law of Practice make a case via statistical analysis that an exponential law usually gives a better approximation to the observed data than a power law does. - JimR 06:57, 14 July 2005 (UTC)

[edit] Cumulative average cost?

Note that http://www.maaw.info/LearningCurveSummary.htm states that in Wright's original model the cost involved is not the unit cost of the last unit, but the cumulative average unit cost. The article does not mention this point at present. I'm not sure if this makes a big enough difference to need remedying. Any ideas? (More generally, in the apparent absence of pointers to evidence of experimental verification of the effect in practice, I wonder whether the precision of the numerical form of the curve is really justified.) - JimR 07:18, 16 July 2005 (UTC)

In the aerospace industry, production estimators use, if not swear by, improvement curve theories. Wright's model, also known as the Cumulative Average Curve, Wright Curve, or Northrop Curve, predicts the cumulative average unit cost while a competing theory, known as the Unit Curve (aka. Crawford Curve, Boeing Curve), is based on the individual unit cost. The government accepts both for proposals, and their usage tends to be dictated by what the given corporation traditionally uses.

You can find out more from the US DoD Defense Procurement site: http://www.acq.osd.mil/dpap/contractpricing/vol2chap7.htm Koreantoast 17:24, 4 October 2006 (UTC)

[edit] Moore's Law

Isn't Moore's law a special case of this?

From the consumer's point of view, sort of (except that the consumer is getting different products as Moore's law grinds ahead, not exactly the same product at successively lower costs). From the producer's point of view, not quite. A quote from the Moore's law article:

As the cost to the consumer of computer power falls, the cost for producers to achieve Moore's Law has the opposite trend: R&D, manufacturing, and test costs have increased steadily with each new generation of chips. As the cost of semiconductor equipment is expected to continue increasing, manufacturers must sell larger and larger quantities of chips to remain profitable. (The cost to tape-out a chip at 0.18um was roughly $300,000 USD. The cost to tape-out a chip at 90nm exceeds $750,000 USD, and the cost is expected to exceed $1.0M USD for 65nm.)

— Teratornis 15:11, 23 August 2006 (UTC)

[edit] The "steep" learning curve misnomer

Learning a Task When I first met the phrase 'learning curve' in the 1950's it was in a book by an industrial phsycologist who said that individuals or small groups learning a job progress slowly at first (getting the fundamentals), then quickly (applying them) and finally slowly (long practice tends toward extra high skill). This leads to an 'S' shaped graph of skill against time. On this basis having "a steep learning curve" implies easy to learn: the opposite what is usually meant.

In any case the "Steep learning curve" is much more commom than other usages and it should be highlighted in the article and given precedence over the more esoteric applications of the phrase. 82.38.97.206 17:23, 11 February 2006 (UTC)mikeL

Actually, I was about to say that "steep learning curve" should indeed be mentioned, but as a misuse of the term. -cp 03:19, 17 April 2006 (UTC)

I will add this to the misnomer article's list of examples. Also, the learning curve article could use an illustrative graph comparing a steep learning curve to a shallow one, to show how a steep curve implies rapid (easy) learning. Perhaps a better descriptor for a difficult learning problem would be stiff, to imply that a given learning curve resists being driven down. Too bad we can't get the word out to millions of people who use the misnomer. — Teratornis 15:11, 23 August 2006 (UTC)

I first encountered the learning curve concept in an article in either Dr. Dobb's Journal or Creative Computing around 1990. The article discussed hypothetical decisions made by a software development firm relating to choosing a new compiler, programming language, programming paradigm, or something similar. If the amount of resources expended to achieve a given level of expertise is measured along the vertical axis, and expertise gained is measured along the horizontal axis, then a more "expensive" learning curve will indeed be steeper (ie, it will have a greater positive slope). I was flabbergasted when first reading this "Experience curve effects" Wikipedia article! The "experience curve" concept seems to me to be virtually unrelated to the "learning curve" concept. The "Learning Curve" idea is this: different approaches to solving a problem (ie, writing a computer program) may be more or less expensive; the "Experience Curve" idea is: using the same problem-solving method over and over gets less and less expensive (ideally).GrouchyDan 20:57, 30 September 2006 (UTC)

[edit] Ebbinghaus?

see de:Lernkurve --Espoo 20:58, 29 June 2006 (UTC)

Interesting. Can somebody please translate this?

Historisch gesehen stammt der Begriff der Lernkurve von Hermann Ebbinghaus (1885), der das Konzept der Lernkurve in seiner Monografie "Über das Gedächtnis" vermutlich als Erster verwendete und somit als Erfinder gelten dürfte. In der Psychologie wird der Begriff der Lernkurve mitunter ohne strikte Definition der x- und y-Achsenzuordnung angewandt, sodass die Frage der Steilheit anhand konkreter Beispiele betrachtet werden muss. Eine erste strikte Definition des Begriffs für die Anwendung in der Betriebswirtschaft stammt von Wright (1927).

It seems to state that the idea of the Learning Curve (Lernkurve) stems from Ebbinghaus in 1885, long before Wright in 1927. But what's the difference between de:Lernkurve and de:Erfahrungskurve? -- JimR 05:57, 1 July 2006 (UTC)

"Historically, the term learning curve comes from Hermann Ebbinghaus(1885), in whose monograph "Über das Gedächtnis" it was probably first used and thus he might be considered the inventor of the concept. In psychology the term "learning curve" is used from time to time without any definition of the x and y axes, so that the the slope of the curve is [supposed to be derived from non-numerical values]. The first strict definition of the term for use in marketing and management is due to Wright(1927)". That, in any event, is the gist, the nub, the kernel.SpikeMolec 22:01, 4 March 2007 (UTC)